(CN) - Federal approval of the key ingredient in Monsanto's Roundup has caused the monarch butterfly population to plummet 90 percent since 1997, environmentalists claim in Federal Court.
In an action filed Friday in Manhattan, the Natural Resources Defense Council (NRDC) says it is concerned for the iconic orange-and-black butterfly because "glyphosate ... has decimated milkweed, the sole food source for monarch caterpillars," as they make their famous migration across North America, the complaint alleges.
The journey from Mexico to Canada and back is 2,500 miles, and continued use of glyphosate puts this annual migration and "distinctive butterfly in peril," the NRDC says.
One of the most widely used pesticides in the U.S., the Environmental Protection Agency first registered glyphosate in 1974 and re-registered it in 1993.
Monsanto uses glyphosate in its herbicide Roundup, and use of the weed killer spread in the 1990s with the creation of genetically engineered "Roundup Ready" crop strains that are resistant to glyphosate. Approximately 90 percent of U.S. corn and soy fields were treated with the chemical in 2011, according to the complaint.
"Since the mid-1990s, the population of monarchs that completes the North American migration and spends winter in Mexico has declined by more than 90 percent," the NRDC claims. "In 1997, approximately one billion monarchs journeyed from summer habitat in the United States and Canada to wintering grounds in Mexico. This winter, only about 56.5 million butterflies - the second lowest number ever measured - reached their winter refuge. The remaining population is so small that a single severe weather event could eradicate it. Scientists have warned that the monarch migration is at risk of vanishing."
About a year before it filed suit, the nonprofit filed an emergency petition with the EPA, seeking an urgent review of the agency's rules for glyphosate and its impact on the monarch butterfly. The NRDC says the EPA never answered the petition.
"In 2002, a single snowstorm on the Mexican wintering grounds killed more monarchs than currently comprise the entire population," the complaint states. "The continued loss of butterflies will make this already imperiled population increasingly vulnerable."
The U.S. Fish and Wildlife Service recognized the serious decline of the monarch butterfly in February, when it pledged $3 million to improve migration habitats for the species, particularly by planting milkweed along the I-35 corridor from Texas to Minnesota.
The NRDC seeks a court order declaring the EPA's failure to respond to its petition unreasonable, and ordering the agency to conduct a special review of the impact of glyphosate to be completed within six months.
For the NRDC, time is of the essence. "The longer EPA delays, the greater the risk we could lose the monarch migration," senior NRDC scientist Sylvia Fallon said in a statement.
In-house counsel Catherine Rahm filed the group's complaint.
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